I think it is the consensus that the 5W40 is the best grade for the Z I personally quite like the Motul 300V as fully synth.
wouldn't see the need for a different oil just because there's an induction kit fitted as the modification is so minimal I don't think it would make a difference
just last week @ the Charity Show! have to say it worked a treat! but no point in using it if you wax it already, it's just for when for example you wash the car, wax it, drive to a show and want to get rid of the dust etc
I got that, BUT the issue will remain if you have to purchase it from Nissan anyway, as the cost wil be ridiculous like the cradles Hopefully it'll work better though